The La Josefina Gold-Silver Project, Hunt Mining's advanced-stage property, is a 528 square-kilometer mineral concession and consists of 15 manifestations of discovery (MD's), which are partially covered by 399 mining claims, or pertenencias.
More than 62,500 meters and over 540 holes have been drilled. A preliminary mineral resource was calculated and filed as part of a NI-43-101 technical report in 2010. In 2011 and 2014, additional drilling and trenching was completed to enhance existing resources, test new exploration areas and develop targets for future drill campaigns.
Located within Patagonia's highly prospective Deseado Massif mining district, La Josefina lies approximately 100km northwest of the Cerro Vanguardia (AngloGold Ashanti) gold-silver mine. The nearest town, Gobernador Gregores, is 120km to the south.
Cerro Cazador S.A., Hunt Mining's 100% owned Argentine subsidiary, won the public bid to explore, develop and mine La Josefina from Fomicruz S.E. in 2007. CCSA subsequently entered into a partnership agreement with Fomicruz, which was later amended in 2012 from a 9% initial ownership interest to a 19% Fomicruz ownership in a joint venture. The agreement also allows for the provincial mining company to exercise a one-time buy-in option of up to a maximum 49% interest in the project, upon the completion of a positive feasibility study. (More complete details are found on the Corporation's MD&A for 2015)
Geology of La Josefina Project, within the Deseado Massif, is characterized by abundant middle-to late-Jurassic Age volcanic and volcaniclastic rock units.
The units are dominated by rhyolitic to rhyodacitic ignimbrite flows and lava domes together with subordinate agglomerates, volcanic breccias and tuffs with minor basalts, andesites and volcanic agglomerates intercalated upward with mafic tuffs, conglomerates and sediments. Faults active during the period of intense Jurassic extension and volcanism generally trend NNW-SSE and form a series of grabens, and horst blocks.
Since Jurassic time, the rocks have been cut by normal faults of several different orientations, but have undergone only a moderate amount of compression. In general, the Jurassic rocks remain relatively undeformed and remain flat to gently dipping, except locally where close to faults, volcanic domes or similar features. Thin Quaternary Age basalt flows conceal about half of the Jurassic Age rocks on the La Josefina project.
The type of mineralization and alteration styles present across the project area are classified as low to medium sulfidation type epithermal deposits.
Gold and silver occur in fissure vein systems localized in structures, often a meter or more wide and hundreds of meters long. They are comprised of quartz veins, stockworks and breccias, that carry gold, silver, electrum and some sulfides, primarily pyrite with lessor amounts of base metal sulfides.
Mineralization is commonly zoned vertically over a few to several hundred meters from a gold and silver rich top to a relatively silver-rich zone with increasing base metals at depth. Vein textures include open spaces with evidence of multiple generations of quartz, reflected as finely banded "colloform" and "textures".
One area is noteworthy for the "sinter" type epithermal mineralization found there. Here precious metals are located both within bonanza-grade "pipeline" feeder-breccia zones and lower grade strata-bound mineralization disbursed throughout, and directly below, the flatling sinter unit.
The gold-silver and base metal mineralization at La Josefina is hosted by rhyolitic volcanics of the Chon Aike Formation, which is the host for most mineral occurrences found throughout the Deseado Massif. With one possible exception the mineralization is a variation of classic, structurally-controlled low-sulfidation epithermal fissure-vein systems with minor amounts of sulfide minerals and alteration primarily silicification, (argillization and sericitization).
The one exception, the Sinter target, is a siliceous exhalite or water lain ash tuff related to fossilized hot spring activity.
Nearly all of the vein systems at La Josefina are steeply-dipping (>60°) to sub-vertical. The textures and other characteristics reported for these veins are indicative of high-level to medium epithermal systems.
This suggests gold-silver mineralization in many veins should extend below the depths tested by the drilling done to date.
Drilling Specifications; Sampling and Analytical Procedures
- All meters drilled consisted of HQ size diamond core (63.5 mm in diameter)
- Core recovery averaged greater than 95%
- Core boxes were closed and shipped from the rig by attending geologists
- All core was unloaded and placed on indoor logging tables by techs
- Geologic staff then completed core recovery and geotechnical logs
- Core was then logged for lithology, structure, alteration and apparent mineralization (mineralized intervals were reviewed again after splitting)
- Geologic staff then typically measured out sample intervals between 0.4 to 1.5 meters in length based on lithology, alteration, structure and apparent mineralization
- Geologists determines symmetry of apparent mineralization then draws a cut line onto the core
- Core was then photographed (both wet and dry) by techs
- Core was then halved by techs with a standard table rock saw (12 inch diamond blade)
- Halved core is placed back in the box and placed on sampling tables
- Geologists then place one half of each sample interval into a marked bag and seals it with a zip tie
- Half of sampled core is retained for check assay and geologic verification
- In each sequence of twenty samples geologist inserts one blank sample (established barren crystal tuff) one core quarter duplicate, and one standard (3 different standards were purchased from an accredited lab and rotated periodically)
- Sealed samples are sorted and stored in a locked container until shipped by truck to bus station for transport to ALS Chemex preparation facility located in Mendoza, Argentina
- An independent report on Hunt Mining's QA/QC procedures is included here
- La Josefina - Maria Belen Averages: view
- La Josefina - Sinter Averages: view
- To view 2011 drill assays as of March 27, 2012 click here (PDF | 204KB).
- To view drill assays prior to 2011 click here (PDF | 904KB).
- To view the NI 43-101 compliant technical report for this project please click here (PDF | 15.9MB).
- To view the NI 43-101 compliant resource estimate for this project please click here (PDF | 5.85MB).
Surface Channel Sampling
- Geologist using paint marks samples intervals in the field.
- Under Geologic Staff supervision (while filling out sample description and location information): parallel cuts are made into the outcrop or trench floors by technicians
- Saw cuts are made to a uniform depth using hand held electric saws
- Sample cuts are made to replicate a halved size piece of HQ core (approximately 64 mm wide by 32 mm deep) (This was true, historically, and is still our target process, but we are presently creating some channels that are narrower)
- Technicians then chisel out the rock between the cuts, bag, seal and transport samples back to camp
- Bagged samples are sorted and QC/QA samples are inserted into each batch of 20 (as described above) (Historically, but not presently our procedure with samples)
Previous exploration valued at $2.8 million was conducted over a thirteen year period by FOMICRUZ and Minamerica including 8,000 surface samples, 3,900 meters of trenching, and 4,100 meters of shallow core drilling. The historical exploration work completed by Fomicruz and Minamérica defined four general target areas in the La Josefina Project as Noreste, Veta Norte, Central, and Piedra Labrada.
Noreste, a 28-square kilometer area in the northeast part of the project, consists of three separate target areas; the most advanced being a sinter layer exposed discontinuously over an area of 2.5 kilometers x 300 meters or more.
Its maximum thickness in outcrop is about 2 meters, dips moderately to the WSW. The best exposure is Mogote Hormigas, a 600-meter long sinter-capped hill bounded on the east by a NW-SE fracture zone that displaces the sinter layer. Examples of high-grade gold over significant lengths of breccia include: 3.0 m @ 176.9 g/t Au and 7.0 m @ 114.1 g/t Au in separate trenches.
Veta Norte is a 3 square kilometers area in the northeast central part of the project between the Noreste and Central target areas. It consists of a prominent north-south fissure vein system, up to 3 meters wide and more than 1,500 meters long. The vein system is divided into 6 separate segments, all which are gold bearing. Outcrop and trench samples contain 2 to 5 g/t gold over lengths of 1 to 4 meters; and 10 of 15 drill holes intersected gold at widths and grades comparable to, or better than, the surface samples.
The Central Area is southwest of Veta Norte and is crossed by at least 8 known vein-veinlet systems exposed in a 2-square-kilometer window through the overlying veneer of Quaternary basalts. The veins are discontinuous sinusoidal bodies up to 3.5 meters wide, 220 to 600 meters long trending NW-SE, concealed in both directions beneath basalt cover. Thirty-two holes drilled to less than 40 meters tested 3 of the 8 known vein systems in the Central Area. Strong mineralization - e.g., from 0.5 to 7 meters with more than 1 g/t gold up to 164 g/t - was intersected in at least 25% of the holes.
Piedra Labrada, in the south-central part of the La Josefina Project, is a 2.5 x 5.0 kilometer area with structural "fairways" containing numerous zones of quartz veinlets and veinlet-stock-works. These zones are a few hundred meters long, up to 15 meters wide, and aligned in NW-SE to NNE-SSW directions over strike lengths of 1 to 2 kilometers. Samples are commonly anomalous in gold, with values up to 9 g/t Au reported.
The historic exploration at La Josefina has produced results, which have been very favorable and in line with results expected from the initial testing of similar high-level epithermal vein systems. In several cases, the results demonstrated good continuity of gold mineralization in three dimensions. The geology and mineralization defined by this initial work suggests the La Josefina vein systems are similar in character and size to other epithermal systems currently being exploited or developed in the region.
Hunt Mining through CCSA acquired the La Josefina project in 2007 and immediately initiated aggressive exploration programs that have to date focused largely on drilling targets previously defined by the exploration and drilling efforts of Minamérica and Fomicruz. A brief summary of the exploration activities undertaken by Hunt Mining from 2007 to 2013:
- Review of existing project data
- Re-logging and re-sampling of core from mineralized intervals of historical drill holes
- Re-mapping and re-sampling of select outcrops and trenches
- Detailed reconnaissance and geologic mapping of the entire La Josefina property position
- Compilation of regional geologic data to better understand structure, stratigraphy, and mineralization
- Completion of 416 line kilometers of IP/Resistivity Survey. The IP/Resistivity Survey was done by AkuBra S.A. (Mendoza, Argentina) and consisted of gradient arrays at 25 meter X 50 meter spacing's over a 5.5-kilometer grid. The technology employed was the same as that proven effective elsewhere in the Deseado Massif (e.g., San José and Cerro Negro). The survey undertaken at La Josefina delineated multiple zones of IP chargeability and resistivity anomalies, even under cover south of exposures in the Veta Sur area
- Drilling, logging and sampling of 242 HQ diamond drill holes totaling 37,556 meters
- Regional analysis and compilation of structural and alteration regimes covering more than 200,000 hectares in western Santa Cruz
- Reconnaissance exploration mapping and sampling of 25 HMX controlled prospects
- Collection and analysis of more than 2,500 stream sediment soil and rock chip samples covering more than 170,00 hectares of HMX controlled exploration ground